DialogSetInfo ( nInfoType, szInfoString, nParameter );
nInfoType:
DLG_INFO_ALTIMAGE—Specifies an alternate bitmap to be displayed in the dialog. If nParameter is set to TRUE, szInfoString should specify the image to be displayed in the dialog. This parameter applies to all InstallShield dialogs that display the standard installation image on the left side of the dialog. For more information, see the nParameter description.
szInfoString:
When DLG_INFO_ALTIMAGE is passed in nInfoType, this parameter specifies the file name of an alternate bitmap to display.
nParameter:TRUE
在Dialog中的大背景的图片在IS的安装目录下：C:Program Files (x86)InstallShield2010ScriptdialogsBitmapId_103.bmp文件.
Splash Screen：在Support Files/Billboards下引入一个bmp的文件，即可在安装程序的时候有启动画面.